Method for producing cast iron rich in carbon



Patented Feb. 7, 1950 METHOD FOR PRODUCING CAST IRON RICH INCARBON Jean Baptiste Deschamps Paris, France, assignors to St (Societe dEtudes, de Recherches and Jacques Bergier, S. E. R. A. P. et dApplications des Poudres agglomeres), Paris, France No Drawing. Application October 16, 1947, Serial No. 780,302. In France November 6, 1946 9 Claims. 1

It is known that the properties of cast iron vary according to the carbon content and the nature of the carbon distribution therein. Gray iron has an iron content of about 95% and a carbon content of 2 to 5%, plus variable percentages of other components su h as silicon, tungsten, sulphur, manganese, phosphorus. By increasing the percentage of carbon, whether in fine particles or in a lump, the properties of the resulting irons may be widely varied from the almost self lubric'a'ting cast iron for bearings, formed by the addition of natural or synthetic graphite, to the high friction coefiicient iron containing either pertoleum or acetylene black, various forms of lamp black or carbon black or of amorphous carbons such as cokes of any origin, or anthracite, etc. Manufacturing methods as hitherto known scarcely permit a higher carbon content than 5% in cast irons.

The present invention has for its object a cast iron rich in carbon and a method whereby the carbon content in cast irons may range from very slight proportions up to 40 This new method is chiefly characterized by the application of high frequency vibrations to ensure a homogeneous distribution of the carbon throughout the molten iron.

These vibrations may be produced directly by a magnetic flux acting on the molten mass.

They may also be obtained by plunging a metal core into the melt and subjecting said core to electrostriction or to magnetostriction.

The invention may be executed in the following practical manner:

Into a crucible a given quantity of gray pig iron is placed with a proportional quantit of carbon varying up to 40% and in the form of lamp black, graphite or other suitable form.

It is preferable to use lamp black for high friction coefficients and'graphite for low friction coeflicients.

The carbon is placed at the bottom of the crucible and the pig iron is placed on top of the carbon, so that the iron may descend as it melts while the carbon which is lighter rises through the molten iron mass, thus promoting the carbon distribution.

It is advantageous to effect this smelting operation in an induction furnace.

During the smelting, an electro-magnetic flux of about 10,000 cycles per second produced by an auxiliary winding is caused to act on the melt, stirring the latter as required.

The melt may also be agitated by means of ultrasonic elastic vibrations produced by a mag- 2 netoor electro-striction oscillator acting upon a metallic core of rather high melting point, penetrating into the melt, the frequency of the ultrasonics employed being above 50,000 cycles per second.

The melt is then cooled progressively by regulating the cooling action according to the'final product desired. As a particular example, in the production of cast iron for brake shoes, in accordance with the braking curve desired, the quality and percentage of the carbon introduced may be varied so as to maintain a high resistance to wear while at the same time keeping the friction coefficient at an appropriate value.

In some particular cases, the carbon component may be replaced by silicon carbide (C'arborundum).

It is understood that the method according to the invention may be modified as to detail and may be applied in various ways Without altering the spirit and scope of the invention.

What We claim is: 1. A process for the production of gray pig iron that is super-saturated in carbon content, comprising in combination, the steps of melting the iron; and incorporating therein an amount of carbon in excess of that required for saturation by subjecting the melt to a high frequency vibration ranging between about 10,000 and 50,000 cycles per second, thereby effecting a homogeneous dispersion of the carbon in the pig iron.

2. A process for the production of gray pig iron that is super-saturated in carbon content, comprising in combination, the steps of melting a gray pig iron having a carbon content of up to 5%; adding further carbon thereto so as to obtain a total carbon content in excess of that required for saturation; and subjecting the melt to a high frequency vibration ranging between about 10,000 and 50,000 cycles per second, thereby effecting a homogeneous dispersion of the carbon in the pig iron.

3. A process for the production of gray pig iron that is super-saturated in carbon content, comprising in combination, the steps of melting a, gray pig iron having a carbon content of up to 5%; up to 35% carbon so as to obtain a total carbon content in excess of that required for saturation; and subjecting the melt to a high frequency vibration ranging between about 10,000 and 50,000 cycles per second, thereby efiecting a homogeneous dispersion of the carbon in the pig iron.

4. A process for the production of gray pig iron that is super-saturated in carbon content, comprising in combination, the steps of melting the iron; and incorporating therein an amount of carbon in excess of that required for saturation by subjecting the melt to a high frequency vibration by means of an electromagnetic flux having an audio-frequency of about 10,000 cycles per second, thereby effecting a homogeneous dispersion of the carbon in the pig iron.

5. A process for the production of gray pig iron that is super-saturated in carbon content, comprising in combination, the steps of melting the iron; and incorporating therein an amount of carbon in excess of that required for saturation by subjecting the melt to a high frequency vibration by means of ultrasonic elastic waves having a frequency in excess of 50,000 cycles per second, thereby effecting a homogeneous dispersion of the carbon in the pig iron.

6. A process for the production of gray pig iron that is super-saturated in carbon content, comprising in combination, the steps of melting the iron; and incorporating therein an amount of carbon in excess of that required for saturation; suspending in the melt a piece of iron; and subjecting the latter to vibrations in excess of 50,000 cycles per second, thereby effecting the homogeneous dispersion of the carbon in the pig iron.

7. A process for the production of gray pig iron that is super-saturated in carbon content, comprising in combination, the steps of melting gray pig iron; adding up to 35% carbon thereto so as to obtain a total carbon content in excess of that required for saturation; and subjecting the melt to a high frequency vibration by means of an electromagnetic flux having an audio-frequency of about 10,000 cycles per second, thereby effecting a homogeneous dispersion of the carbon in the pig iron.

8. A process for the production of gray pig iron that is super-saturated in carbon content, comprising in combination, the steps of melting gray pig iron; adding up to carbon thereto so as to obtain a total carbon content in excess of that required for saturation; and subjecting the melt to a high frequency vibration by means of ultrasonic elastic waves having a frequency in excess of 50,000 cycles per second, thereby effecting a homogeneous dispersion of the carbon in the pig iron.

9. A process for the production of gray pig iron that is super-saturated in carbon content, comprising in combination, the steps of melting gray pig iron; adding up to 35% carbon thereto so as to obtain a total carbon content in excess of that required for saturation; suspending in the bath a piece of iron; and subjecting the latter to vibrations in excess of 50,000 cycles per second, thereby effecting the homogeneous dispersion of the carbon in the pig iron.

JEAN BAPTISTE DESCHAMPS. JACQUES BERGIER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

1. A PROCESS FOR THE PRODUCTION OF GRAY PIG IRON THAT IS SUPER-SATURATED IN CARBON CONTENT, COMPRISING IN COMBINATION, THE STEPS OF MELTING THE IRON; AND INCORPORATING THEREIN AN AMOUNT OF CARBON IN EXCESS OF THAT REQUIRED FOR SATURATION BY SUBJECTING THE MELT TO A HIGH FREQUENCY VIBRATION RANGING BETWEEN ABOUT 10,000 AND 50,000 CYCLES PER SECOND, THEREBY EFFECTING A HOMOGENEOUS DISPERSION OF THE CARBON IN THE PIG IRON. 